Regardless of your financial situation or education, building wealth boils down to three things: Saving, resourcefulness, and maximizing income, according to William D. Danko, coauthor of the best-seller „The Millionaire Next Door.“

His latest book, „Richer Than a Millionaire,“ posits the idea that true prosperity is the convergence of good health, happiness, and wealth.

In a recent Q&A with the Washington Post, Danko was asked for his best advice for building wealth „regardless of financial situation and education.“ Danko said:

„First, commit to saving 20% of your income. Currently, most save about 5%. It is hard to get ahead and be an investor without saving first.

Second, be a good steward of your resources. This includes having stable personal relationships, and good personal habits. These behaviors will lead to a longer life, and more compounding opportunities.

Third, consider having more than one stream of income. A second job can be beneficial.“

Danko calls it a „stretch goal“ — you may not be able to save that much now, but it’s what you should aim for.

„If you earn and spend everything, you cannot build a significant financial net worth,“ he said in the Q&A. „You must practice self-imposed financial scarcity. So, if you make $100,000, create a lifestyle that only requires 80% of this, and save/invest the rest.“

Research backs up Danko’s point that having a healthy personal life will lead to a longer life — studies show that fostering friendship is key to aging well and boosting happiness, Business Insider’s Erin Brodwin reported. And so do personal habits, like tweaking your diet and getting the right kind of exercise.

Finally, the more income you’re generating, the more money you’ll be able to save, so long as you don’t fall victim to „lifestyle creep.“ This will also help you generate passive income, which one financial expert called „the holy grail of ways to make money.“

In fact, one Business Insider contributor has seven separate streams of income, from blogging to real estate, and he says it means he’ll never stop earning money.